Cloutier G, Allard L, Durand L G
Laboratoire de génie biomédical, Institut de recherches cliniques de Montréal, Québec, Canada.
J Biomech Eng. 1996 Aug;118(3):318-25. doi: 10.1115/1.2796013.
Blood turbulence downstream of a concentric 86 percent area reduction stenosis was characterized using absolute and relative Doppler spectral broadening measurements, relative Doppler velocity fluctuation, and Doppler backscattered power. Bidimensional mappings of each Doppler index were obtained using a 10 MHz pulsed-wave Doppler system. Calf red cells suspended in a saline solution were used to scatter ultrasound and were circulated in an in vitro steady flow loop model. Results showed that the absolute spectral broadening was not a good index of turbulence because it was strongly affected by the deceleration of the jet and by the shear layer between the jet and the recirculation zones. Relative Doppler spectral broadening (absolute broadening divided by the frequency shift), velocity fluctuation, and Doppler power indices provided consistent mapping of the centerline axial variation of turbulence evaluated by hot-film anemometry. The best agreement between the hot-film and Doppler ultrasound methods was however obtained with the Doppler back-scattered power. The most consistent bidimensional mapping of the flow characteristics downstream of the stenosis was also observed with the Doppler power index. The relative broadening and the velocity fluctuation produced artifacts in the shear layer and in the recirculation zones. Power Doppler imaging is a new emerging technique that may provide reliable in vivo characterization of blood flow turbulence.
利用绝对和相对多普勒频谱展宽测量、相对多普勒速度波动以及多普勒背向散射功率，对同心面积缩小86%狭窄下游的血液湍流进行了表征。使用10MHz脉冲波多普勒系统获得每个多普勒指数的二维映射图。悬浮在盐溶液中的小牛红细胞用于散射超声，并在体外稳流环模型中循环。结果表明，绝对频谱展宽不是湍流的良好指标，因为它受到射流减速以及射流与再循环区之间剪切层的强烈影响。相对多普勒频谱展宽（绝对展宽除以频移）、速度波动和多普勒功率指数提供了通过热膜风速仪评估的湍流中心线轴向变化的一致映射图。然而，热膜法与多普勒超声法之间的最佳一致性是通过多普勒背向散射功率获得的。用多普勒功率指数也观察到了狭窄下游流动特性最一致的二维映射图。相对展宽和速度波动在剪切层和再循环区产生伪像。功率多普勒成像术是一种新兴技术，可能为血流湍流提供可靠的体内特征描述。
